Large Scale Human Impacts As the human population is rapidly increases, humans are creating larger environmental changes. Two major concerns are: – Ozone depletion – Global climate change

Ozone Layer a layer of concentrated ozone gas made up of three oxygen molecules (O 3 ) between 20 and 50 kilometers above Earth’s surface absorbing harmful UV radiation UV-c = most harmful UV-b = main cause of most sun burns UV-a = least harmful

Ozone Depletion – Since the 1970’s scientists have been finding evidence that the ozone layer was thinning Holes in the ozone layer were eventually found above both poles – Ozone holes caused by CFCs (chlorofluorocarbons) which break down ozone molecules

Ozone cont… Destruction of the ozone layer has increased the ultraviolet radiation reaching Earth’s surface. chlorofluorocarbons - chemicals used in refrigeration (Freon) and aerosol cans, and in certain manufacturing processes Ozone Depletion protects from UV rays Loss of ozone above Arctic

Progression of atmospheric damage

Impacts Ozone layer absorbs most of the harmful UV-B radiation more UV-B means: – more melanoma and non-melanoma skin cancers – more eye cataracts – weakened immune systems – reduced plant yields – damage to ocean eco-ecosystems- kills producers- phytoplankton – more damage to plastics

Effects of loss of Ozone Wrinkles & SKIN CANCER

Ozone Success A phase out of cfc’s was enacted in 1987 In 2000 the majority of governments banned the use of cfc’s Ozone depletion has now slowed, and recovery is expected over the next years

Global Climate Change As human consumption of fossil fuel has increased, so has our emissions of green house gasses As these gasses have accumulated in our atmosphere, they have contributed to a change in the average temperature and climate on earth= global climate change

Climate Change A 0.5°C increase in the average temperature of the biosphere has occurred in the past 120 years (abiotic factor) – Natural variations do contribute to the variation in climate – However, human activities are adding carbon dioxide and other greenhouse gases into the atmosphere, making the atmosphere retain more heat More carbon dioxide from burning fossil fuels, cutting down trees and burning forests

How it works… Greenhouse Gasses trap and redirect infrared radiation back to the earth. This causes warming, like a car in the sun The greenhouse effect is actually beneficial- without it, earth would be too cold to support much life.

Different surfaces reflect different amount of light/radiation What happens when the glaciers melt??

Most Important Greenhouse Gases Source: U.S. EPA 2005 GHGs: Water: H 2 O Carbon Dioxide: CO 2 Methane: CH 4 Source Examples: Oceans, Rivers, Plants, Soil Combustion, Respiration, deforestation + burning Wetlands, Oceans, Combustion, Animals (thawing permafrost) PCC slide no. 034

Sources of anthropogenic greenhouse gases (2007) Source: U.S. EPA 2009 by gasby sector

Methane By Source

U.S European Union Russia 68.4 Ukraine 21.7 Poland 14.4 China 57.6 Japan 31.2 Australia 7.6 India 15.5 Kazakhstan 10.1 South Africa 8.5 Canada 14.9 Mexico 7.8 Trinidad and Tobago United Arab Emirat es Kuwait Total CO 2 emissions Between in billions of tons TIME magazine, 2001 US: 4% of world’s total population 25% of the world’s greenhouse gases China:25% of the world’s population 8.5% of the world’s greenhouse gases (since 1950)

China emission

How cars generate CO 2 Source: Murray 2005 CH O 2  CO 2 + H 2 O 6.3 lb/gal 20 lb/gal PCC slide no. 005

Climate Change v. Climate Variability We see the sum of both Climate variability (e.g. Natural swings) Climate change (e.g. warming trend) Time (years) "climate"

More Evidence: Ice Cores Ice layers preserve information about each year Sources: NOAA, GISP2 websitesPCC slide no. 036

Correlations

Carbon dioxide (CO 2 ) and other greenhouse gases warm the planet Human activities have increased the concentration of the major greenhouse gases since Average global temperature has increased 1.3°F since Warming since the 1950s very likely (>90% chance) due to human increases in GHG Scientific Consensus on Climate Change +35% +142% +18% Figure source: IPCC

Future climate change Source: IPCC 2007PCC slide no. 008

Effects It may result in rising sea level causing more frequent and more severe weather disturbances Environmental changes benefit some species, but greatly disturb others that may not survive

Effects 1.Increase in the global temperature. 2.Melting of polar ice caps and glaciers. 1.Sea level rise- displaces people and habitats 3.Changes in the climate of certain areas of the world. 4.Increase in the number and severity of extreme weather events – hurricanes and tornadoes. – Increased droughts in certain areas of the world – Increased flooding worldwide 5.Decreased biodiversity in the coral reefs and rainforests. 6.May affect food production in key food producing nations.

Sea Level Rise Melting of – Greenland Ice Sheet – Antarctic Ice Sheet – Glaciers and ice caps Expansion of heated (warm) sea water  C warming by ~2100  meter rise in sea level IPCC (2007)

Arctic Sea Ice (in September) data from National Snow and Ice Data Center (Boulder, CO, USA) million km million km 2 sea ice edge (where normally found)

Loss of Sea Ice PCC slide no. 038 Source: Arctic Council 2004

Could be a runaway process

Solar energy Production of oxygen Storage and recycling of nutrients Regulation of climate Purification of water and air Storage and distribution of fresh water Food production Nursery habits for wildlife Detoxification of human and industrial waste Natural pest and disease control Management of soil erosion and runoff Section 6-4 Ecosystem services are provided, but it’s your responsibility to help save the Earth! Go to Section:

The Value of a Healthy Biosphere What we have to remember: – A healthy biosphere provides us with many valuable goods and services (food, medicine, temperature control, water purification, soil formation, etc) Make wise choices about resources used, disposal, recycling, and energy conservation